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381 results on '"Altan, T."'

52. Land use changes in relation to coastal tourism developments in Turkish Mediterranean

Author

Atik M., Altan T., Artar M., and Çukurova Üniversitesi

Subjects
South Antalya Region, Tourism impact, Environment, Land use change
Abstract

Tourism is one of the major driving forces behind land use and landscape changes in the coastal Mediterranean. The aim of this study is to analyze the land use changes in relation to coastal tourism developments in the Turkish Mediterranean. Spatial and quantitative inventory of land use changes was delineated by interpreting physical land use data for 1974, 1988, 1990 and 1996 in GIS systems. Study results showed that 816 hectares of agricultural land and 457 hectares of natural coastal forest are converted to tourism-based establishments such as hotels, service buildings and settlements. Degradation of the coastal forests was higher in the beginning of tourism developments, but this trend has become static while constant change on agricultural lands was expected to continue in the coming years. Therefore, it is crucial that tourism development plans be accompanied with a set of ecological, social and economic system for the livelihood of tourism and the operated area.

Published
2010

57. Measurement and Interpretation of Flow Stress Data for the Simulation of Metal-Forming Processes

Author

AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS AND MANUFACTURING DIRECTORATE, Semiatin, S. L., Altan, T., AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS AND MANUFACTURING DIRECTORATE, Semiatin, S. L., and Altan, T.

Abstract

Slip activity, Burgers vector populations, and dislocation densities were determined by X-ray line-profile analysis of peaks from individual grains in a bulk polycrystalline sample. The method was tested at the focused X-ray beamline ID11 at the European Synchrotron Research Facility (ESRF) in Grenoble, France and was applied to a bulk commercial purity titanium specimen for which slip activity was determined for 49 single grains. The most-active slip systems were of and type, and the orientation of the stresses acting on these slip systems revealed a spread due to the effect of neighborhood grains on plastic response. The new x-ray method can provide input for crystal-plasticity analyses and permits experimental verification of the results of numerical calculations which was not possible before., Journal article preprint. Prepared in cooperation with The Ohio State University.

Published
2010

60. Computer-aided analysis and design of the shape rolling process for producing turbine engine airfoils

Author

Lahoti, G. D, Akgerman, N, and Altan, T

Subjects
Aircraft Propulsion And Power
Abstract

Mild steel (AISI 1018) was selected as model cold rolling material and Ti-6A1-4V and Inconel 718 were selected as typical hot rolling and cold rolling alloys, respectively. The flow stress and workability of these alloys were characterized and friction factor at the roll/workpiece interface was determined at their respective working conditions by conducting ring tests. Computer-aided mathematical models for predicting metal flow and stresses, and for simulating the shape rolling process were developed. These models utilized the upper bound and the slab methods of analysis, and were capable of predicting the lateral spread, roll separating force, roll torque, and local stresses, strains and strain rates. This computer-aided design system was also capable of simulating the actual rolling process, and thereby designing the roll pass schedule in rolling of an airfoil or a similar shape.

Published
1978

65. Influence of Cutting Edge Radius of Coated Tool in Orthogonal Cutting of Alloy Steel.

Author

Rech, J., Yen, Y.-C., Hamdi, H., Altan, T., Bouzakis, K. D., Ghosh, S., Castro, J.C., and Lee, J.K.

Subjects
SIMULATION methods & models, MACHINING, CUTTING (Materials), ALLOYS, MECHANICS (Physics), MATERIALS science
Abstract

This paper investigates the effects of edge radius of a round-edge PVD coated tool upon chip formation, cutting forces, and tool stresses in orthogonal cutting of an alloy steel 42CrMo4 (AISI 4142H). A comprehensive experimental approach based on end turning of thin-walled tubes is conducted using advanced coated tools with well-defined cutting edge radii ranging from 9 to 28 microns. In parallel, 2-D finite element cutting simulations based on Lagrangian thermo-viscoplastic formulation are used to analyze cutting temperature and tool stress distributions within the coating layer and tool substrate. The results obtained from this study provide a fundamental understanding of the cutting mechanics for the coated tool used and can assist in the optimization of tool edge design for more complex geometries such as chamfered edge. Particularly, the results obtained from the experiments and simulations of this study have underlined that there exists an optimum cutting edge radius that minimizes tool stresses, especially within the coating layer, and prolongs the tool life. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

Published
2004
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93. A practical method for estimating forging loads with the use of a programmable calculator.

Author

Subramanian, T. and Altan, T.

Abstract

The forging engineer must often estimate the load necessary in a press forging operation. Thus, the appropriate press capacity can be selected and, in some cases, it can be decided whether or not in-house capability exists for quoting on a given forging. This paper describes a simple load calculation method and its application to forging a steel connecting rod. The results, obtained with a hand calculator, are evaluated by comparing them with the results of computer-aided analysis and with experimental forging data. This comparison indicated that hand calculator results are sufficiently accurate for estimating forging loads and stresses. It is expected that the technique, described in this paper, will be a useful tool for the engineers in forge shop practice. [ABSTRACT FROM AUTHOR]

Published
1978
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95. Process fusion: tube hydroforming and crushing in a square die.

Author

Hwang, Y. M. and Altan, T.

Subjects
FINITE element method, NUMERICAL analysis, MACHINERY, MECHANICAL engineering, SIMULATION methods & models, SYSTEMS engineering, MATHEMATICAL notation, CRUSHING machinery
Abstract

The objectives of this study are to evaluate the quality of the tubes formed by process fusion: hydroforming and crushing. The plastic flow pattern of the tubes during the process fusion in a square cross-sectional die is explored. Finite element simulations using the commercial software DEFORM for the tube expansion test and process fusion of circular tubes formed into a square cross-section have been conducted. The tubes in the process fusion have larger diameter and smaller thickness than the tubes used in the expansion test. The relationship between the forming pressurization and loading pass is discussed. Comparisons of the simulation results such as thickness distribution of the formed product, clamping force and forming pressure for the expansion test and process fusion are made. It is known that the internal pressures and the clamping forces of the die needed in process fusion are much less than those in the expansion test. The thickness distribution obtained by process fusion is much more uniform than that obtained in the expansion test. [ABSTRACT FROM AUTHOR]

Published
2004
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96. ODTÜ Mimarlık Tarihi 30. Yılını Kutluyor.

Author

Elvan Altan, T., Özgenel, Lale, and Arslan, Pelin Yoncacı

Abstract

Copyright of Mimarlık is the property of Chamber of Architects in Turkey and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Published
2019

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